Sayyidah Umm Salamah (may Allah be pleased with her) said: The Prophet (peace and blessings be upon him) would make the intention to fast during the night, then in the morning he would say: "Do you have anything (to eat)?" We would say: We have nothing; are you not fasting?
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20271